In a blade board system, each blade or circuit board contains components such as microprocessors, memory, network, interfaces, disk drives, etc., depending on the blade's intended function. The terms blade, blade board, circuit board and board are used interchangeably and have the same definition. The circuit boards plug into slots or sockets in a bus which interconnects the boards. Buses are used to distribute signals between or among components or subsystems such as memories or processors, for example.
After the assembling of a blade board, the manufacturer executes a number of tests that do not require the board to be powered such as in-circuit tests and flying-probe tests. Most severe errors such as noise, misplaced components and bad soldering are found during logic tests. Logic tests are performed by executing programs. To perform logic tests, it is necessary to attach power to the board and execute logic tests on the microprocessor to test the assembled parts like memory, I/O chips, to name a few. As the power level increases, the microprocessor generates excess heat which must be dissipated by some means. Conventionally, a heat sink, a thermally conductive device, is used to dissipate heat from one or more circuit board components into the surrounding air. Typically, a heat sink is mounted to a circuit board component.
Conventional approaches of mounting a heat sink include screwing the heat sink onto the board or using an adhesive to be applied to the heat sink which is then directly placed onto the circuit board component. Both approaches require additional time spent during the manufacturing process. For example, when using the adhesive approach, pressure must be applied to the heat sink for a strict amount of time to provide adequate holding strength. Similarly, screwing the heat sink to the board requires careful attention paid to where the screws are secured and to whether the screws have scratched or cut the surface of the circuit board.
Due to time constraints and possible damage from the adhesive or screws to the circuit board if the heat sink were removed, the heat sinks stay permanently fixed on the board during manufacturing. There are several disadvantages of fixing a heat sink to the circuit board during this early circuit board manufacturing phase. One disadvantage is that using screws to secure the heat sink utilizes space immediately around the circuit board component. Specifically, screwed heat sinks cover more area then the components themselves, which means, that it is not possible to access parts under the heat sink for measurements or reworks. Another disadvantage is that removing heat sinks mounted by adhesive requires thermal treatment of the adhesive, which is a time consuming process and is likely to damage the circuit board component such as a chip.